Embolus Removal Device with Blood Flow Restriction and Related Methods

ABSTRACT

A clot removal device has an expandable treatment member having a distal tip and a proximal end, a delivery wire having a distal end coupled to the proximal end of the expandable treatment member, and a flow restrictor carried along the delivery wire at a location that is separate and proximal from the expandable treatment member. The flow restrictor has a body with a distal section and a proximal section, the distal section being covered and the proximal section being uncovered. The expandable treatment member is moveable relative to the flow restrictor, and can be retracted into the distal section.

RELATED CASES

This application claims priority from U.S. Provisional Application Ser.No. 62/249,249, filed on Oct. 31, 2015, and U.S. Provisional ApplicationSer. No. 62/251,069, filed on Nov. 4, 2015, the contents of each ofwhich are incorporated by this reference as if fully set forth herein intheir entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to devices and methods usefulfor clot retrieval, and removal devices to treat, among other things,ischemic stroke.

Description of the Prior Art

Currently, the FDA-approved treatment options for an acute ischemicstroke include intravenous (IV) delivery of clot dissolving medicine andmechanical thrombectomy.

For treatment use, clot dissolving medicine, such as the thrombolyticagent (Tissue Plasminogen Activator (t-PA)), is injected into thevasculature to dissolve blood clots that are blocking blood flow to theneurovasculature. Intravenous t-PA is currently limited in use becauseit must be used within a three-hour window from the onset of a strokeand can result in an increased risk of bleeding. This standard of careleaves room for upgrade, and is only the appropriate approach totreatment for a limited class of individuals, groups andtemporally-limited exigent cases.

A second option includes the use of mechanical thrombectomy devices.Such devices are designed to physically capture an embolus or clot, andto remove it from the blocked vessel, thereby restoring blood flow. Themajor advantage of the mechanical thrombectomy device is it can expandthe treatment window from three hours to over ten hours.

Some existing mechanical thrombectomy devices used for increasing bloodflow through an obstructed blood vessel include; 1) a filter trapdesigned and built to collect and remove emboli; 2) a cork-screwguidewire-like device to retrieve embolus; and 3) a stent-like deviceconnected to a delivery wire to retrieve embolus. All of these devicessuffer from certain disadvantages.

First, filter-type thrombectomy devices tend to be cumbersome anddifficult to deliver and deploy, and a larger-profile guide catheter maybe needed to fully remove the embolus. In addition, it is difficult tocoordinate precise and predictable movement to position the deviceproperly in the vessel. The device can drift within the vessel, twist,or not be adequately conforming to the vessel wall and, therefore noteffective for removing embolus.

Cork-screw guidewire devices can only capture and remove emboli that arefirm, or subject to certain mechanical variables such as being heldtogether by itself as one piece. Cork-screw guidewire devices are noteffective in removing particulate matter that may be scattered or brokenup.

Stent-like mechanical thrombectomy devices are not capable of capturingsmall emboli that break off from a large embolus (if any), and can leadto complications such as the blockage of distal smaller vessels, vesseldissection, perforation, and hemorrhage arising as a result ofover-manipulation in the vessel.

The disadvantages common to all of the devices described above include,for example: 1) the device may capture an embolus, but then lose graspof it and migrate/deposit it incidentally into another area of theneurovasculature, creating the potential for a new stroke in a differentpart of the neurovasculature; 2) the device is not capable of capturingsmall embolus breaking off from the larger embolus and preventing itfrom migrating to a more distal area of the neurovasculature; 3) therelative large device profile prevents these devices from treating thedistal smaller diameter vessels; and 4) risk of sICH (symptomaticIntra-cerebral Hemorrhage) after intra-arterial clot removal in acutestroke patients.

Other flaws in the current mechanical thrombectomy designs include poorvisibility/radiopacity, lack of variation in the delivery portion toenhance and improve deliverability, and lack of coatings or modifiedsurface textures on the treatment portion to enhance embolus affinity,etc. In conclusion, there is a great need for improved devices, systems,and methods for restoring blood flow through a blood vessel. None of theexisting medical mechanical thrombectomy devices address all necessaryneeds to date.

SUMMARY OF THE DISCLOSURE

The present invention is directed to a method and devices for removingclots, emboli and other luminal blockages from a blood vessel. A clotremoval device is provided, having an expandable treatment member havinga distal tip and a proximal end, a delivery wire having a distal endcoupled to the proximal end of the expandable treatment member, and aflow restrictor carried along the delivery wire at a location that isseparate and proximal from the expandable treatment member. The flowrestrictor has a body with a distal section and a proximal section, thedistal section being covered and the proximal section being uncovered.An access catheter is delivered to a location proximal to a location ofa clot or embolus in a blood vessel, and then the clot removal device isdelivered through a lumen in the access catheter to the location of theclot or embolus in the blood vessel. The expandable treatment member isexpanded at a location that is at or distal to the location of the clotor embolus, and the clot or embolus is caught in, or engaged with, theexpandable treatment member. The access catheter is then positioned withrespect to the flow restrictor such that the uncovered proximal sectionis completely covered by the distal end of the access catheter and thecovered distal section forms a seal with the distal end of the accesscatheter, and then aspiration is applied through the access catheter andthrough the uncovered proximal section to remove the clot or embolusfrom the blood vessel.

The clot removal device of the present invention can also be used inaccordance with another method, where the clot removal device isdelivered to a location of a clot or embolus in a blood vessel, theexpandable treatment member is expanded at a location that is at ordistal to the location of the clot or embolus, the clot or embolus iscaught in, or engaged with, the expandable treatment member, theexpandable treatment member is withdrawn into the distal section of theflow restrictor, and the expandable treatment member and the flowrestrictor are withdrawn from the blood vessel.

The devices of the present invention can be made from either metallicbiocompatible material (such as Nitinol, stainless steel, Co—Cr basealloy, Ta, Ti, etc.) or polymer based biocompatible material (polymerswith shape memory effect, PTFE, HDPE, LDPE, Dacron, Polyester, etc.).For ischemic stroke treatment, the expandable treatment member must beflexible enough to negotiate the torturous vasculature of the brain andwithout modifying the vessel profile at the target location. The profileof the expandable treatment member must be small enough to reach targettreatment site as known to artisans.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a fully expanded clot removal device accordingto a first embodiment of the present invention.

FIG. 2 is a side view of the clot removal device of FIG. 1 shown in acompacted orientation inside a microcatheter.

FIG. 3A is a side view of the clot removal device of FIGS. 1 and 2 shownwith the expandable treatment member fully pushed outside themicrocatheter,

FIG. 3B is a side view of the clot removal device of FIGS. 1 and 2 shownwith the control arms and the expandable treatment member slightlypushed outside the microcatheter,

FIG. 4 is a side view of a fully expanded clot removal device accordingto a second embodiment of the present invention.

FIG. 5 is a side view of the clot removal device of FIG. 4 showing thecollection of a clot in a vessel,

FIG. 6A is a side view of the clot removal device of FIG. 4 showing theclot collected inside the expandable treatment member.

FIG. 6B is a side view of the clot removal device of FIG. 4 showing theclot collected inside the expandable treatment member, and theexpandable treatment member inside the proximal flow restrictor.

FIG. 7 is a side view of a fully expanded clot removal device accordingto a third embodiment of the present invention shown with a clot caughton the surface of, and between the cell spaces, of the expandabletreatment member.

FIG. 8 is a side view of the clot removal device of FIG. 7 showing theexpandable treatment member being pulled into the proximal flowrestrictor.

FIG. 9 is a side view of the clot removal device of FIG. 7 showing theexpandable treatment member inside the proximal flow restrictor.

FIG. 10 is a side view of a fully expanded clot removal device accordingto a fourth embodiment of the present invention,

FIG. 11 is a side view of the removal device of FIG. 10 showing theexpandable treatment member being pulled into the proximal flowrestrictor with the clot engaged on its outer surface.

FIG. 12 is a side view of the removal device of FIG. 10 showing theexpandable treatment member inside the proximal flow restrictor.

FIG. 13A is an enlarged side view of an exemplary proximal flowrestrictor design,

FIG. 13B is an enlarged side view of an exemplary proximal flowrestrictor design with a push wire connected from the proximal end.

FIG. 13C is an enlarged side view of an exemplary proximal flowrestrictor design with a through lumen on the delivery element from theproximal end,

FIG. 14A is an exemplary application of the proximal flow restrictor ofFIG. 13B combined with an access catheter, such as a guide catheter, orother procedure support catheters (not in aspiration position).

FIG. 14B is an exemplary application of the proximal flow restrictor ofFIG. 13B combined with an access catheter, such as a guide catheter, orother procedure support catheters, in an aspiration position.

FIGS. 15A-15C illustrate another embodiment of the clot removal deviceaccording to the present invention where the expandable treatment memberis omitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplatedmodes of carrying out the invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of illustratinggeneral principles of embodiments of the invention. The scope of theinvention is best defined by the appended claims.

The present invention is directed to a device for removing emboli andother luminal blockages. The device includes an expandable treatmentmember, such as a mesh or a cage, that is associated with a proximalflow restrictor. During treatment, the expandable treatment member ispositioned within or distal to an embolus within a blood vessel and thentransitioned into an expanded state. In certain embodiments, theexpandable treatment member's normal state is the expandedconfiguration, and the expandable treatment member is compacted anddelivered to the treatment site in the compacted configuration through adelivery sheath or catheter. The expandable treatment member is deployedfrom the delivery sheath, which causes it to return to its normalexpanded profile by the elastic energy stored in the device. Expansionof the expandable treatment member engages the expandable treatmentmember with the emboli or clot at the blockage. In addition, theproximal flow restrictor can also expand to a larger diameter state whenit is deployed from the delivery sheath or catheter. Expansion of theproximal flow restrictor advantageously limits or restricts forwardblood flow and creates a pressure gradient within the blood vesselbetween locations distal and proximal to the flow restrictor. Thepressure gradient helps to prevent the clots from being flushed awayfrom the treatment member, thereby assisting in removal of the embolusfrom the blood vessel, Specifically, the pressure difference can actlike a vacuum to assist in removal of the embolus from the blood vessel.After expansion, the expandable treatment member and the emboli engagedwith the expandable treatment member are removed from the blood vessel.During clot removal, the expandable treatment member (with the bloodclot engaged) can also be pulled inside the proximal flow restrictorfirst (i.e., the clot retrieval component with clots engaged are housedinside proximal restrictor), and then pulled back into guide catheter,and removed from the blood vessel. Furthermore, aspiration/vacuumsuction can be applied through the lumen of the access catheter lumenand proximal flow restrictor to prevent clots from breaking off andflowing downstream.

In addition, the proximal flow restrictor regulates the forward bloodflow and allows the controlled (gradual) restoration of the blood flow,and reduces the risk of sICH (symptomatic Intra-cerebral Hemorrhage)after intra-arterial clot removal in acute stroke patients.

Devices of the present invention are suitable for removal of blockagesin body lumens, and are particularly well-suited for removal of thrombi,emboli, or atheroma in the vasculature, including those in arteries andveins. It is understood that the dimensions of the device may bemodified to suit a particular application. For example, devices of theinvention used for treatment of deep vein thrombosis may have a largercross-section than devices of the invention used for treatment of brainischemic.

Compared with existing mechanical thrombectomy devices, the uniquedevice design included in this invention has the advantage of providinga proximal flow restriction feature to block the forward flow of bloodwhen the device is deployed during use. This feature can help toeliminate or reduce the risk of flush, or the break-up of the bloodclots during the procedure.

Another important advantage provided by the present invention is thecentral lumen of the proximal flow restrictor can be used or combinedwith the lumen of the access catheter to apply aspiration/suction forceto help with the complete removal of the blood clots in the vasculature.

Thus, the device described in the present invention overcomes theshortcomings of the existing technologies and can be delivered to thetarget vasculature smoothly, can be retrieved safely, and can remove theentire embolus with fewer passes. In use, the mechanical thrombectomydevice described in the present invention can be compacted to a lowprofile and loaded onto a delivery system and delivered to the targetlocation in the vessel by a medical procedure such as through use of adelivery catheter. The mechanical thrombectomy device can be releasedfrom the delivery system when it reaches the target implant site andexpanded to its normal expanded profile by the elastic energy stored inthe device (self-expandable device).

As for the relative position of the expandable treatment member inrelation to the embolus or blood clot, it can either be deployed at thesite of the embolus, or deployed distal to the embolus. In dealing withlong embolus, the expandable treatment member can also be used to removethe embolus from the proximal portion to the distal portion withmultiple passes, until the entire embolus is removed.

Turning now to the drawings, FIGS. 1-2 illustrate a device 100 forremoving emboli and other luminal blockages according to the presentinvention. The device 100 can be made from one piece or multiple piecesof Nitinol™ super elastic material or Nitinol™ super-elastic alloytubing. It can also be made from other biocompatible materials thatexhibit super-elastic or shape memory properties. The device 100 can bemade by laser cutting, mechanical machining, chemical machining,electrochemical machining, EDM, braiding and related techniques known tothose skilled in the art.

The device 100 has an expandable treatment member 102 carried along adelivery wire 104 adjacent the distal end of the delivery wire 104, Thedelivery wire 104 has a soft distal tip 106 that extends distal from theexpandable treatment member 102, and has a marker coil embedded therein.A plurality of laser cut control arms 108 couple the proximal portion ofthe expandable treatment member 102 with a hub 110 along the deliverywire 104, Specifically, each control arm 108 has opposite endsconnecting the proximal portion of the expandable treatment member 102and the hub 110. A proximal flow restrictor 112 is carried on thedelivery wire 104 proximal to the hub 110. Marker bands or marker coilscan be incorporated into the proximal flow restrictor 112 and theexpandable treatment member 102 for visibility. At least one end of theproximal flow restrictor 112 can move freely along the delivery wire104.

The expandable treatment member 102 can be configured to act as a catchbasket for the clot or embolus, and in this embodiment is shaped as acone in its fully expanded configuration, with an apex 120 at thedistal-most portion of the expandable treatment member 102 secured tothe delivery wire 104 adjacent the distal tip 106, and with theexpandable treatment member 102 increasing radially in diameter untilreaching its proximal-most ring 122, The expandable treatment member 102can be made of a Nitinol™ braided mesh and can be shape-set to the coneshape by a thermal mechanical process. Most significantly, theexpandable treatment member 102 is not cylindrical in configurationwhich allows it to better conform to the vessel contour and to move morefreely inside the vessel. The size of the opening for the ring 122 canrange from 0.5 mm to 12 mm. The length of the distal cone portion fromthe apex 120 to the ring 122 can range from 2 mm to 40 mm.

The meshed frame of the expandable treatment member 102 can be providedwith a plurality of openings. Frame members or struts form the body ofthe meshed frame and define the plurality of openings. In certainembodiments, the frame members are a plurality of intersecting wires orother threads. The frame members may form a mesh or cage-like structurethat defines the plurality of openings. In certain embodiments, theexpandable treatment member 102 can include a plurality of protrusions150 on the frame. See FIG. 1 The plurality of protrusions 150 furtherengages the embolus for removal.

As an alternative to, or in addition to, the plurality of protrusions150, the expandable treatment member 102 may include one or more surfacemodifications or treatments. For example, as explained in greater detailbelow, the surface of the expandable treatment member 102 may beroughened to improve clot adhesion. The main geometrical axis of theexpandable treatment member 102 can be offset or different from thelongitudinal center axis of the native blood vessel. When the expandabletreatment member 102 is in use, both the delivery catheter (e.g.,microcatheter 124) and/or the movement axis of the expandable treatmentmember 102 can be different from the longitudinal central axis of thevessel, and can contact the side wall of the blood vessel.

The delivery wire 104 can be made of super-elastic Nitinol wire,stainless steel wire, braided stainless steel wire, Co—Cr alloy andother biocompatible materials. The diameter of the delivery wire 104 canrange from 0.008″ to 0.030″, and the delivery wire 104 can have variablediameters/stiffness along its length.

This distal tip 106 can be made of Ta, Pt, W, Pt—W, or Pt—Ir alloys forradiopacity, and from radiopaque coils or markers.

The control arms 108 can be laser-cut from a super-elastic Nitinolmaterial. They are preferably taut when the expandable treatment member102 is in its full expanded configuration. The control arms 108 functionto control the opening diameter of the ring 122, so that the largestdiameter of the ring 122 can be achieved when the control arms 108 arecompletely pushed out of the sheath of a microcatheter 124 (see FIG. 2).The diameter of the ring 122 can be adjusted by the length of thecontrol arms 108 being pushed out of the microcatheter 124. Even thoughthe present embodiments are being described as having three control arms108, it is possible to provide one, or more than two, control arms 108.

The hub 110 can be made from radiopaque materials, and can move freelyalong, and with respect to, the delivery wire 104. The hub 110 can alsobe secured to a fixed location along the delivery wire 104

The proximal flow restrictor 112 can be a bulbous structure and can bemade of a Nitinol™ mesh, and it is fixedly connected to the deliverywire 104 at its proximal end, while the distal end of the proximal flowrestrictor 112 can move freely along, and with respect to, the deliverywire 104. In another embodiment, the proximal flow restrictor 112 can befixedly connected to the delivery wire 104 at its distal end, while theproximal end of the proximal flow restrictor 112 can move freely along,and with respect to, the delivery wire 104. The proximal flow restrictor112 can have a first smaller compacted profile for delivery through themicrocatheter 124 possible. The proximal flow restrictor 112 can have asecond larger expanded diameter/profile when released from themicrocatheter 124 or other delivery system to block, limit, or restrictthe blood flow. The bulbous structure can be a braided or laser cutstructure, and made from a film, membrane, braided or netted material.In certain embodiments, the proximal flow restrictor 112 is a polymericfilm or membrane. In other embodiments, the proximal flow restrictor 112is a braided or woven net formed from a metal, polymer, or combinationthereof. The type and material of the proximal flow restrictor 212 maybe chosen based on the desired coverage (i.e. amount of flow to berestricted). The surface of the proximal flow restrictor can be eitherentirely or partially covered by some polymer materials to restrict theblood flow. It can be fabricated from the one or two element(s) of thedevice 100, or fabricated from other pieces of material, then attachedto the delivery wire 104 by mechanical means, or via a thermal (laser orsoldering) process, or adhesive/glue, or heat shrink technology. Thebulbous structure can also be fabricated from the same piece of Nitinol™tubing as that of the device 100 by laser cutting or chemical processesand then shape-set to a larger diameter than the raw Nitinol™ tubing.

The proximal flow restrictor 112 can have a diameter in its fullyexpanded configuration that is about the same as the diameter of theopening ring 122 of the expandable treatment member 102 when theexpandable treatment member 102 is in its fully expanded configuration.The diameter of the proximal flow restrictor 112 can range from 0.5 mmto 12 mm, and its length can range from 2 mm to 60 mm.

Radiopaque markers can be attached on any portion of the device 100 forpositioning. One way to provide full visibility for the device 100 is torun a radiopaque material through the entire or partial lumen of thedelivery wire 104. Markers can also be placed on the expandabletreatment member 102 to aid in positioning. In vu addition, radiopaquemarkers (marker coils, marker bands, radiopaque wire(s), radiopaquecoatings, etc.) can be integrated into the proximal flow restrictor 112.

The device 100 can have a surface treatment on selected portions toimprove performance for the selected portions of the device 100. Boththe proximal flow restrictor 112 and the expandable treatment member 102can either be coated or covered, entirely or partially, by typicalbiocompatible materials for lubricity. The surface of the expandabletreatment member 102 can have either a positive or negative charge forimproved clot adhesion. The surface of the expandable treatment member102 can also be either mechanically or chemically treated to have a“rough” surface for improved clot adhesion. The “rough” surface can beachieved by (i) a porous surface coating or layer (ii) a micro blastedsurface or micropinning, or (iii) an irregular strut geometry orarrangement.

The expandable treatment member 102 can be fully or partially coatedwith chemical(s), drug(s) or other bioagents to prevent clotting and/orfor the better adhesion between the device and embolus. In addition, thesurfaces of the expandable treatment member 102 and the proximal flowrestrictor 112 can be treated to form different surface layers (e.g.,oxidation layer, Nitro or carbonized or N—C-combined surface layer,etc.) for better adhesion between the expandable treatment member 102and the embolus.

FIG. 2 shows the device 100 compressed and fitted inside a microcatheter124. In use, a guide wire can be inserted through the vasculature to thetarget treatment site, and then the microcatheter 124 is delivered overthe guide wire to a target location in a vessel with the device 100housed therein using conventional delivery techniques that are known tothose skilled in the art. Alternatively, the microcatheter 124 can beinserted over the guide wire first, then the compacted device 100 can beinserted through the inner lumen of the microcatheter 124. The distalend of the microcatheter 124 can be positioned proximal to, or inside,or distal to, the clot or embolus at the target location, and there isno need for the microcatheter 124 to traverse the clot or embolus,thereby minimizing the possibility of pushing the clot or embolusdownstream in the vessel.

The microcatheter 124 can then be pulled back (proximally) to exposefirst the expandable treatment member 102 (see FIG. 3A), then thecontrol arms 108, and then later on the proximal flow restrictor 112.Before the control arms 108 are fully exposed, the expandable treatmentmember 102 will not reach its full diameter, which makes it possible forthe expandable treatment member 102 to not disturb clots before thedevice 100 reaches its desired position. Instead of pulling back themicrocatheter 124, it is also possible to deploy the expandabletreatment member 102 by inserting the device 100 into the microcatheter124 until the distal tip 106 reaches the distal end of the microcatheter124, and then holding the proximal end of the microcatheter 124 in astationary position, pushing the device 100 distally out of themicrocatheter 124. Under this alternative, there is no need to withdrawthe microcatheter 124, which allows the positioning to be more accurate.The expandable treatment member 102 will not fully deploy (i.e., reachits largest diameter) until the control arms 108 have been completelypushed out of the microcatheter 124. This allows for a gap, volume, orspace (see FIG. 3B) between the expandable treatment member 102 and theactual clot in the vessel, so that the clot will not be pusheddownstream and dislodged by the expandable treatment member 102 when theexpandable treatment member 102 is pushed out of the microcatheter 124and located distal to the clot. Once the control arms 108 have beencompletely pushed out of the microcatheter 124, then the expandabletreatment member 102 will reach its full diameter to catch the clot fromthe distal side of the clot. At this point, the microcatheter 124 andthe elongated delivery wire 102 will be pulled back or withdrawn at thesame time to remove the clot.

During this procedure, the proximal flow restrictor 112 eliminates orreduces the forward blood flow to minimize the risk of poor clotretention and clot dislodgement. The expandable treatment member 102 cancollect all the clots/emboli to prevent them from flowing downstream.The proximal flow restrictor 112 also regulates the flow of blood duringand immediately after the procedure to eliminate the effect of sICH fora better clinical outcome.

In other embodiments, the proximal flow restrictor can surround (i) anouter surface or diameter of a proximal portion of the expandabletreatment member, or (ii) both the inner and outer surfaces or diametersof the proximal portion of the expandable treatment member. In theseembodiments, the proximal flow restrictor can cover a length extendingbetween (i) a proximal end of the expandable treatment member to abouthalf of the length of the expandable treatment member, or (ii) between aproximal end of the expandable treatment member to about one-quarter ofthe length of the expandable treatment member.

For example, FIGS. 4-6 illustrate another embodiment of a device 200 forremoving emboli and other luminal blockages. The device 200 also has anexpandable treatment member 202, a soft distal tip 206 (with markedcoil), a delivery wire 204, control arms 208, a hub 210 and a proximalflow restrictor 212 that correspond to the expandable treatment member102, soft distal tip 106 (with marked coil), delivery wire 104, controlarms 108, hub 110 and proximal flow restrictor 112, respectively, forthe first embodiment, except for a few differences.

First, the expandable treatment member 202 has a slightly differentconfiguration. Instead of the conical configuration of the expandabletreatment member 102, the expandable treatment member 202 has afrusto-conical body 228 where its distal-most end does not terminate inan apex, but has a small distal opening.

Second, the proximal flow restrictor 212 has a different configuration,having a body that includes a cylindrical distal section 230 and agenerally conical (or frusta-conical) proximal section 232 that has atapering configuration. The two sections 230 and 232 combine to define areceiving section.

The body 228 and the sections 230 and 232 can all be laser cut from thesame material (e.g., a Nitinol™ tubing or sheet), but the sizes of thecells or openings 234 in the body 228 and the sections 230 and 232 canbe varied to vary the flexibility of the different body 228 or sections230, 232. The section 232 can have an annular distal edge 240 thatfunctions as an open mouth. The sections 230 and 232 can also havedifferent size/porosity, and can either be covered by a biocompatiblepolymer or left uncovered. One example is to leave the section 232uncovered, while covering section 230. The uncovered section 232 can beincorporated with other access catheters to facilitate theaspiration/suction function. The proximal flow restrictor 112 can have abraided configuration.

Third, the delivery wire 204 can have a deflected section 238 extendingdistally from the section 230 at an angle with respect to the centrallongitudinal axis to the hub 210, which is offset from the centrallongitudinal axis occupied by the delivery wire 204. In this regard, thecontrol arms 208 extend from the hub 210 towards the body 228 atdifferent angles. The different angles allows the expandable treatmentmember 202 to navigate the vascular anatomy more easily, and also betterfacilitates the collection of clots and particles by the expandabletreatment member 202. In addition, the different angles for the controlarms 208 allow the proximal opening of the expandable treatment member202 to remain open, and not to collapse, during the procedure. Thedifferent angles also makes it easier for the control arms 208 tocontrol the diameter or staged deployment of the expandable treatmentmember 202 during the procedure.

The proximal flow restrictor 212 is configured so that it can experiencerelative movement with respect to the expandable treatment member 202.This is accomplished by not having a fixed connection between theproximal flow restrictor 212 and the delivery wire 204, and by allowingthe proximal flow restrictor 212 to slide along the delivery wire 204.In other words, the expandable treatment member 202 can move independentof the proximal flow restrictor 212. This provides a more effectivecapture and removal of the clot as described below.

In use, the device 200 is loaded inside a microcatheter 124, which isdelivered to a target location in a vessel with the device 200 housedtherein using conventional delivery techniques that are known to thoseskilled in the art. The distal end of the microcatheter 124 can again bepositioned proximal to, or inside, the clot or embolus at the targetlocation, and there is no need for the microcatheter 124 to traverse theclot or embolus. The device 200 can then be pushed distally out of thedistal end of the microcatheter 124 to expose first the expandabletreatment member 202 and then later on the proximal flow restrictor 212.See FIG. 5. The device 200 is then pulled back or withdrawn so that theexpandable treatment member 202 catches the clot. See FIG. 6A. When thedelivery wire 204 is pulled back and the expandable treatment member 202is pulled back with it, the proximal flow restrictor 212 can stay at thesame location within the vessel, so that when the annular distal edge240 of the proximal flow restrictor 212 contacts the annular proximaledge or ring 222 of the body 228, and further proximal pulling of thedelivery wire 204 will cause the expandable treatment member 202 to bepulled back into the cylindrical section 230 so that the entire device200 is removed from the vessel. As a result, the entire clot or emboluscan be retained inside a cage defined by the expandable treatment member202 and the proximal flow restrictor 212 during removal so as to preventdislodgement or disengagement of the clot. See FIG. 6B. The expandeddiameter of the annular proximal edge 222 is preferably slightly smallerthan the expanded diameter of the cylindrical section 230 and itsannular proximal edge 240 so that the expandable treatment member 202can be retained inside the cylindrical section 230.

In addition, it is possible to provide the delivery wire 204 with alumen that opens at an opening that is located inside the proximal flowrestrictor 212 (see FIGS. 13-14 below), so that suction can be appliedfrom the proximal end of the access guide catheters or microcatheter 124to pull smaller clots and particles into the proximal flow restrictor212 using suction force, and then removed from the vessel.

Finally, the suction/aspiration action through the lumen of the accessdevices and the encapsulation of the expandable treatment member 102(with clot engaged) can happen either simultaneously or in sequenceduring the procedure.

FIGS. 7-9 illustrate another embodiment of a device 300 for removingemboli and other luminal blockages. The device 300 is similar to thedevice 200 in that it also has an expandable treatment member 302, adelivery wire 304, a hub 310 and a proximal flow restrictor 312 thatcorrespond to the expandable treatment member 202, delivery wire 204,hub 210 and proximal flow restrictor 212, respectively, for the secondembodiment, except for a few differences.

First, the expandable treatment member 302 has a differentconfiguration, and can be configured as any of the removal devicesdisclosed in co-pending United States Publication No. 2015-0150672,filed Jan. 16, 2015, whose entire disclosure is incorporated by thisreference as if set forth fully herein. For this reason, there are nocontrol wires 108/208.

Second, the proximal flow restrictor 312 can be essentially the same asthe proximal flow restrictor 212 in FIGS. 4-6.

Third, the hub 310 can function as a marker or stopper. During theprocedure, when the expandable treatment member 302 is being pulledback, the expandable treatment member 302 will start to pull theproximal flow restrictor 312 with it once the hub 310 reaches andengages the proximal end of the inside of the proximal flow restrictor312. At this stage, the entire (or portion of) expandable treatmentmember 302 with its collected clot would already be retained inside theproximal flow restrictor 312, Again, suction force can be applied fromthe proximal end of the access guide catheter or microcatheter to helppull all the clots/emboli inside the proximal flow restrictor 312.

Again, the body of the expandable treatment member 302 and the sectionsof the proximal flow restrictor 312 can all be laser cut from the samematerial (e.g., a Nitinol™ tubing or sheet), but the sizes of the cellsor openings in the expandable treatment member 302 and the proximal flowrestrictor 312 can be varied to achieve varying flexibilities. Theproximal tapered portion on the proximal flow restrictor 312 can beuncovered, while the straight portion of the proximal flow restrictor312 can be covered, to achieve the desired suction effect and suctioncontrol.

As shown in FIG. 7, the clot can be caught on the surface of, andbetween the cell spaces, of the expandable treatment member 302, and theexpandable treatment member 302 pulled inside the proximal flowrestrictor 312 (see FIGS. 8-9) completely before the entire system(microcatheter and device 300) is removed from the blood vessel. Sincethe proximal flow restrictor 312 has no fixed joint with the deliverywire 304, it can remain in a fixed location with respect to the deliverywire 304 and the expandable treatment member 302 so that the expandabletreatment member 302 (with the blood clot engaged thereon) can be pulledinside the proximal flow restrictor 312. The expandable treatment member302 can be pulled into the proximal flow restrictor 312 until the hub310 (acting as a stopper) contacts the narrowed portion of the proximalsection 332 of the proximal flow restrictor 312. The proximal portion ofthe expandable treatment member 302 has a tapered configuration so thatit can fit into the narrowed proximal section 332. At this time, theproximal flow restrictor 312 will move together with the expandabletreatment member 302 (and blood clot housed inside) when the deliverywire 304 is pulled out. The device 300 can be pulled inside a guidecatheter for removal out of the vessel, or can be removed out of thevessel without being pulled inside a guide catheter first. Again,suction force can be applied from the proximal end of the access guidecatheter or microcatheter to help pull all the clots/embolus inside theproximal flow restrictor 312.

FIGS. 10-12 illustrate another embodiment of a device 400 for removingemboli and other luminal blockages. The device 400 is similar to thedevice 100 in that it also has an expandable treatment member 402, adelivery wire 404, distal tip 406 and a proximal flow restrictor 412that correspond to the expandable treatment member 102, delivery wire104, distal tip 106 and proximal flow restrictor 112, respectively, forthe first embodiment, except for a few differences.

First, the expandable treatment member 402 has a differentconfiguration, and has a distal section 440 that is essentially the sameas the conical body of the expandable treatment member 102, However, theexpandable treatment member 402 also has a proximal section 442 that isalso conically shaped with an apex 444 at its proximal end and with itslargest diameter portion coupled to the largest-diameter portion of thedistal section 440. The double tapered configuration of the expandabletreatment member 402 allows its distal end to be softer and lesstraumatic, and also provides a less stiff proximal end, which togetherallow for easier navigation of the vessel anatomy. The distal expandabletreatment portion 402 can be either entirely or partially covered bypolymer materials to block the blood flow (flow from distal portion ofthe vessel to proximal portion of the vessel, so that the aspirationeffect from the access catheter and proximal flow restrictor will bemore effective).

Second, the proximal flow restrictor 412 can be essentially the same asthe proximal flow restrictor 212 in FIGS. 4-6.

Third, there is no hub 110 and no control wires 108/208.

Again, the body of the expandable treatment member 402 and the sectionsof the proximal flow restrictor 412 can all be laser cut from the samematerial (e.g., a Nitinol™ tubing or sheet), but the sizes of the cellsor openings in the expandable treatment member 402 and the proximal flowrestrictor 412 can be varied to achieve varying flexibilities.

The clot can be engaged on the outside of the distal section 442 (seeFIG. 11) and the expandable treatment member 402 can be pulled insidethe proximal flow restrictor 412 (see FIGS. 11 and 12) completely beforethe entire system (microcatheter and device 300) is removed from theblood vessel, Since the proximal flow restrictor 412 has no fixed jointwith the delivery wire 404, it can remain in a fixed location withrespect to the delivery wire 404 and the expandable treatment member 402so that the expandable treatment member 402 (with the blood clot engagedon its outer surface) can be pulled inside the proximal flow restrictor412. The aspiration can be applied during the procedure through thelumen of the access catheter or microcatheter and the proximal flowrestrictor as well.

FIGS. 13A, 13B, and 13C show some exemplary design configurations forthe braided proximal flow restrictor. The proximal flow restrictor shownin FIGS. 13A-13C and 14A-14B can be the same the proximal flowrestrictor 212, although the principles and concepts embodied in FIGS.13A-13C and 14A-14B also apply to the other proximal flow restrictorsshown and described herein.

As shown in FIG. 13B, the proximal flow restrictor 212 can have acentral lumen 260 at the proximal end 262, a tapering proximal portion232, and a cylindrical distal portion 230. The proximal portion 232 canbe uncovered, and the distal portion 230 can be covered by biocompatiblepolymer materials. In use, suction can be applied through the centrallumen 260 from the access catheters.

As shown in FIG. 13B, a push wire 264 can be connected to the proximalportion 232 to operate the proximal flow restrictor 212. This design canbe used or incorporated with other commercially-available clot removaldevices, and can also be used or incorporated with an access catheter,guide catheter, DAC, or microcatheter to apply suction during the clotremoval procedure.

As shown in FIG. 13C, a different central lumen structure 260 a having alumen can be connected to the proximal portion 232 to operate theproximal flow restrictor 212. This design can be used or incorporatedwith other commercially-available clot removal devices, and can also beused or incorporated with an access catheter, guide catheter, DAC, ormicrocatheter to apply suction during the clot removal procedure.

FIGS. 14A and 14B show an exemplary application of the proximal flowrestriction feature. The proximal portion 232 can be fully uncovered orpartially uncovered, and the distal portion 230 can be covered bybiocompatible polymer materials. In use, the proximal flow restrictor212 can be delivered to the target location through a microcatheter orother access catheter 224. The proximal central lumen 260 can be used toslide along a guidewire or the push wire 264 of the clot retrievaldevice. Adjusting the relative position/location of the microcatheter224 with that of the proximal flow restrictor 212, the proximal flowrestrictor 212 can either allow proximal forward flow, or cut off theforward flow. In the situation where forward flow is cut off, thesuction effect can be applied through the lumen of the microcatheter 224for improved clot collection, retention and removal. For example, whenthe push wire 264 connected to the proximal flow restrictor 212 ispulled back towards the access catheter or microcatheter 224, and theuncovered proximal portion 232 is completely covered by the distal endof the access catheter or microcatheter 224 with the covered distalportion 230 forming a seal with the distal end of the access catheter ormicrocatheter 224, the forward flow is totally cut off, and then theaspiration/suction can be applied from the proximal end of the accesscatheter or microcatheter 224 to help retain and collect clots (as shownin FIG. 14B). From FIG. 14B, it is noted that the outer diameter of theaccess catheter 224 is less than the outer diameter of the fullyexpanded distal portion 230, but that this seal can still be formed whenthe proximal end of the distal portion 230 is pulled into the distalopening of the access catheter 224 as the proximal part of the distalportion 230 begins to compress and assume a tapered configuration as thedistal portion 230 is pulled into the access catheter 224.

FIGS. 15A-15C illustrate a different embodiment of the presentinvention, where the device 200 comprises only the flow restrictor 212and the push wire 264, and where the expandable treatment member 202 isomitted. As shown in FIG. 15A, the distal portion 230 is positionedproximal to the blood clot or embolus, and the relativeposition/location of the access catheter 224 is adjusted by operatingthe push wire 264, so that the proximal portion 232 of the flowrestrictor is covered by the distal end of the access catheter 224.Aspiration is then applied to the lumen of the access catheter 224 tosuction or aspirate the blood clot into the distal portion 230 and/orproximal portion 232 (see FIG. 15B), and then the entire flow restrictor212 (including the clot inside) is pulled into the access catheter 224(see FIG. 15C), and the device 200 is removed out of the blood vessel.

As an alternative, if the embodiment shown in FIG. 13C is used, theaspiration can be applied though the central lumen 260 a, instead ofthrough the access catheter 224.

Thus, the embodiment of FIGS. 13C and 15A-15C show that the expandabletreatment member 202 can be omitted and the flow restrictor 212 itselfcan be used to remove blood clots or embolus. The structural arrangementof the flow restrictor 212 (uncovered proximal portion 232 and covereddistal portion 230) facilitates this type of removal.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

1-17. (canceled)
 18. A method for removing a clot or embolus from ablood vessel, comprising: providing a clot removal device, comprising: adelivery wire; a flow restrictor carried along the delivery wire andhaving a body with a distal section and a proximal section, the flowrestrictor assuming an expanded configuration and an unexpandedconfiguration, wherein the distal section is covered and the proximalsection is uncovered in both the expanded and unexpanded configurations;delivering an access catheter to a location proximal to a location of aclot or embolus in a blood vessel; delivering the clot removal devicethrough a lumen in the access catheter to the location of the clot orembolus in the blood vessel; positioning the access catheter withrespect to the flow restrictor such that the uncovered proximal sectionis completely covered by the distal end of the access catheter and thecovered distal section forms a seal with the distal end of the accesscatheter; and applying aspiration through the access catheter andthrough the uncovered proximal section to draw the clot or embolus intothe distal section of the flow restrictor; removing the clot or embolusfrom the distal section of the flow restrictor.
 19. The method of claim18, further including the step of withdrawing the flow restrictor fromthe blood vessel.
 20. The method of claim 18, wherein the uncoveredproximal section has a smaller diameter than the covered distal section.21. The method of claim 18, wherein the uncovered proximal section istapered and the covered distal section is cylindrical.
 22. The method ofclaim 18, wherein the expandable treatment member is configured todefine a catch basket.
 23. A system for removing a clot or embolus froma blood vessel, comprising: a delivery wire; a flow restrictor carriedalong the delivery wire, and having a body with a distal section and aproximal section, with the body defining an outer surface that extendsfrom the proximal section to the distal section, and a distal mouth atthe distal section, the flow restrictor assuming an expandedconfiguration and an unexpanded configuration, wherein the outer surfaceof the distal section is circumferentially covered by a biocompatiblepolymer coating in a manner such that the distal mouth is uncovered, andthe outer surface of the proximal section is uncovered, in both theexpanded and unexpanded configurations; and an access catheter having adistal end and which is deployed to the location of the clot or embolusin the blood vessel and positioned with respect to the flow restrictorsuch that the uncovered proximal section is completely covered by thedistal end of the access catheter and the covered distal section forms aseal with the distal end of the access catheter.
 24. The system of claim23, wherein the uncovered proximal section has a smaller diameter thanthe covered distal section.
 25. The system of claim 23, wherein theuncovered proximal section is tapered and the covered distal section iscylindrical.
 26. The system of claim 23, wherein the expandabletreatment member is configured to define a catch basket.